package com.collection;

import java.util.concurrent.ConcurrentHashMap;

public class ConcurrentHashMapTest {

    public static void main(String[] args) {
        testCHashMapKeyisNull();
    }



    public static void testCHashMapKeyisNull(){
        ConcurrentHashMap chashmap = new ConcurrentHashMap();
        chashmap.put(null,"123");
        System.out.println(chashmap.get(null));
    }
}
